1. Field of the Invention
The present invention relates to a key comprising a bell or dome-shaped key member of elastic material, an edge limiting the open side of the key member being pinched between a base plate and a key housing.
2. Description of the Prior Art
A key of the type set forth above is generally known from the German published application No. 30 41 470, incorporated herein by this reference. The key member referred to in that publication as a sealing membrane has its flat outer edge seated on the surface of a supporting part referred therein as a base plate and is pressed against the base plate by a housing part referred to therein as a screwed cover. As a consequence, the space in which the contacts of the key are located and which is surrounded by the key member and the base plate is sealed from the environment, particularly on the operating side of the key, so that no foreign body can enter into the contact space formed by the key member and the base plate, at least not from the operating side.
The key known from the aforementioned German published application No. 30 41 470 is also useable as a key module so that a keyboard can be formed of a plurality of such keys which are secured to a plate.
Given this known key, however, a disc separate from the plate carries the fixed contacts of the key.
In order to simplify such keys, there is a desire to dispose the fixed contacts directly on a plate to which the key is secured. In such a case, in particular, the number of parts of which the key is composed can be further reduced. The outer edge of the key member can then be pinched between a housing part of the key and the plate.
It is desirable, particularly when equipping such plates with keys, if as few key parts, to be manipulated separately from one another, exist.